The present inventive concept herein relates to a beating signal monitoring module, and a terahertz wave generation device and an optical signal monitoring device that include the beating signal monitoring module.
A terahertz wave is an electromagnetic wave having a frequency between a micro-wave and an infrared light. As a technology for generating a terahertz wave, a method of using a beating signal and photo mixer is recently being studied.
A beating signal is generated by beating two lights having different frequencies from each other generated from two lasers. The generated beating signal is input to a photo mixer. The beating signal being input is absorbed into an activation layer of the photo mixer and generates photo carrier pairs. The generated carriers generate photoelectric current while being moved by an external bias voltage.
A frequency of the photoelectric current is determined in response to a frequency of the beating signal being provided. An electromagnetic, that is, a terahertz wave is emitted in response to the generated photoelectric current. To control a frequency and amplitude of the terahertz wave, a characteristic (e.g., a frequency, a polarization and amplitude) of the two lights generating the beating signal has to be monitored.